Physical well-being is an assumed, though generally unmeasured, condition in studies of the child's psychological development and behavior. There is little developmental inquiry concerning the effects of loss or absence of physical well-being on child development, despite the reality that acute or chronic ill health from disease or accident is, to a great or small degree, part of the life of every child. This project will investigate the psychological and social impact of serious illness (cancer) on children and those in their social network (namely their families, peers and medical personnel who care for them). Areas of research include coping abilities, the influence of the social system of the child and the mutual influences of the stressed children and those of his social network. Observations and interviews will be employed.